The relationship between gastrointestinal disorders and infections with Helicobacter pylori proposed in 1983 by Warren (Warren J R Lancet 1983;1.1273) is well established today. A number of different therapies have been proposed for treatment of H. pylori infections. Most of these therapies comprise different combinations of antibacterial compounds. Some of these therapies also comprise a bismuth compound, see for instance WO 89/03219 (Borody). Other combination therapies comprise a proton pump inhibitor and one or more antibacterial compounds, for instance a combined regimen of omeprazole and amoxicillin which has been approved by regulatory authorities in for example Great Britain and Sweden for the treatment of H. pylori infections. Different triple therapies, for example omeprazole, clarithromycin and amoxicillin or other antibacterial substances, have recently been reported at the 10.sup.th World Congresses of Gastroenterology in October 1994. Some published patent applications in this field are for instance:
WO 93/00327, Astra Aktiebolag, which discloses the combination of a substance with inhibiting effect on the gastric acid secretion which increases the intragastric pH and an acid degradable antibacterial compound. The proposed combination is especially suitable for the treatment of H. pylori infections.
WO 92/03135, Smithkline & French Laboratories, which discloses a combination of a benzimidazole and an anti-Helicobacter agent, i.e. for instance pantoprazole in combination with amoxicillin and/or metronidazole.
In these proposed combination therapies each single active substance is administred separately in different dosage forms, each one comprising only one single active substance. It is well known that patient compliance is a main factor in receiving a good result in medical treatments, especially in the treatment of H. pylori infections. Administration of two, three or even more different tablets to the patient is not convenient or satisfactory to achieve the most optimal results. The present invention now provides new oral dosage forms comprising two or more different active substances combined in one fixed unit dosage form, preferably a tablet.
It is well known that proton pump inhibitors are susceptible to degradation/transformation in acid reacting and neutral media. In respect of the stability properties, it is obvious that one of the active substances being a proton pump inhibitor must be protected from contact with acidic gastric juice by an enteric coating layer. There are different enteric coating layered preparations of omeprazole as well as other proton pump inhibitors described in the prior art, see for example U.S. Pat. No. 4,786,505 (A B Hassle).
There are problems to produce a fixed unit dosage form comprising a rather high amount of active substances. Different active substances in the same preparation give further problems. Preparation of a multiple unit tableted dosage form raises specific problems when enteric coating layered pellets containing acid susceptible proton pump inhibitors as active substance are compressed into tablets. If the enteric coating layer does not withstand the compression of the pellets into a tablet the susceptible active substance will be destroyed upon administration by penetrating acidic gastric juice, i.e. the acid resistance of the enteric coating layer of the pellets will not be sufficient in the tablet after compression.